An archive-type (recordable-type) storage system (hereinafter referred to as “archive storage system”) is used as a device for collectively storing contents, which are data that need not be updated, such as images.
A disk array area, which is a storing destination of the contents in the archive storage system, is formed by a plurality of file systems, which are storage devices such as hard disks. When the archive storage system receives a content storage request from a host such as a server or a client device, the archive storage system writes contents to a file system in the receiving order. When the archive storage system may not write the next content because the free space in the file system to which the contents are written decreases, the archive storage system writes the content and the following contents received after the content to another new file system.
As depicted in FIG. 6, an archive storage system including a four file systems FS1, FS2, FS3, and FS4 will be described as an example. FIG. 6 is a diagram depicting an example of a conventional archive storage system. As depicted in FIG. 6, the archive storage system stores contents received from a host in the file systems in order from FS1 to FS 4. When a content e is stored, if FS1 has no area in which the next content f is stored, the archive storage system stores the content f in the next file system FS2. Further, when a content j is stored, if FS2 has no area in which the next content k is stored, the archive storage system stores the content k in the next file system FS3. Further, when a content o is stored, if FS3 has no area in which the next content p is stored, the archive storage system stores the content p in the next file system FS4. In this way, the archive storage system writes contents, for which a write request is received from the host, to the file systems.
Japanese Laid-open Patent Publication No. 2006-215954 and Japanese Laid-open Patent Publication No. 2007-141089 are examples of related art.
However, in the conventional art, there is a problem that many useless free spaces that are not used are generated on the file systems. For example, the problem will be described using FIG. 6 as an example. It is assumed that, when the content e is stored, FS1 has 10 MB of free space, and the size of the content f that is a content to be stored next is 11 MB. In this case, even though FS1 is short by only 1 MB to store the content f, the content f is stored in the next file system FS2. Hence, the 10 MB in FS1 will be a useless free space.
Such a situation also occurs in FS2, FS3, and FS4, and a useless free space that is not used is generated on each file system. Therefore, in the entire file systems, there are large amounts of useless spaces, and thus the file systems may not be used efficiently.